1. Technical Field
A cleaning solution is disclosed for removing photoresist materials remaining on underlying layer patterns formed by photolithography process using the photoresist patterns as etching mask.
2. Description of the Related Art
Conventional cleaning solutions for removing photoresist materials remaining on the top portion of an underlying layer are generally organic solvents having amine present in an amount ranging from about 20 to about 40 wt. % of the solution and a mixture of H2O2, H2SO4 and H2O.
However, conventional cleaning solutions are environmentally harmful because they include excessive amounts of the amine compounds. The conventional cleaning solutions also have a problem in that they are expensive.
Additionally, in order to remove photoresist materials, a substrate should be soaked in the solution at a temperature greater than 50° C. for about 20 to 30 minutes. This process results in a decrease in productivity.
Further, the mixture of H2O2, H2SO4 and H2O erodes metal, and therefore, an underlying layer pattern is deformed when the underlying layer is metal such as aluminum (Al) or tungsten (W).
In addition, the mixture of H2O2, H2SO4 and H2O is less effective in cleaning photoresists than a solvent having a large quantity of amine. And, when impurities are removed, a process needs to be performed at a high temperature of 50 to 120° C. Therefore, special procedures are required.
FIG. 6 is a SEM photograph of a formed aluminum pattern (33) after cleaning the remaining photoresist on the aluminum pattern using a conventional cleaning solution of H2O2, H2SO4 and H2O. As shown in FIG. 6, the lateral surface of the aluminum pattern is severely damaged when the photoresist remaining on the aluminum pattern is cleaned with the conventional mixture.
FIG. 7 is a SEM photograph of a formed tungsten pattern (43) after cleaning the remaining photoresist on the tungsten pattern using a conventional cleaning solution of H2O2, H2SO4 and H2O. As shown in FIG. 7, the lateral surface of the tungsten pattern is also severely damaged when the photoresist remaining on the tungsten pattern is cleaned with the conventional mixture.